Halecium frigidum Pena Cantero 2010

Halecium frigidum Peña Cantero, 2010

Halecium frigidum Peña Cantero, 2010: 766 –768, fig. 4c–f; 2012: 857, fig. 3g.

Diagnosis. Polysiphonic stems, up to 95 mm high. Branching regular, stem giving rise alternately every third hydrotheca to paired branches forming two distinct, longitudinal series. Branches originating from hydrophore of primary hydrotheca. Hydrothecae alternately arranged in one plane. Hydrotheca at the end of very long, free hydrophore. Hydrothecal diameter slightly increasing distally; rim not everted. A secondary hydrotheca sometimes present. Gonothecae unknown. Cnidome consisting of microbasic mastigophores? and microbasic euryteles?

Remarks. There is nothing to add to the previous description of the species (cf. Peña Cantero 2010), except a better delimitation of the nematocyst size from the holotype (in µm): range 9–10 x 4.5–5, 9.4±0.3 x 4.7±0.2 (n=6); ratio, range 1.9–2.2, mean 2.0±0.1 (n=6).

Ecology and distribution. Apparently a shelf species, recorded at depths between 216 (Peña Cantero 2010) and 540 m (Peña Cantero 2012), epilithic on gravel and pebbles and basibiont for stolonal colonies of Stegopoma plicatile (Peña Cantero 2012).

West Antarctic distribution (Peña Cantero 2012): the South Orkney Islands (Peña Cantero & García Carrascosa 1995), Peter I Island (Peña Cantero 2010) and the Bellingshausen Sea (Peña Cantero 2012).